In a fluid system, such as a compressed air system, bistable solenoid valves permit displacement between two valve positions, wherein the two valve positions can be maintained when the solenoid valve is in a non-energised state. Generally, the bistable solenoid valve comprises a permanent magnet device and an armature, which can be displaced relative to said permanent magnet device and which has energisable armature coils. Depending upon the energisation of a first armature coil or second armature coil, the armature can be displaced into its first armature position or second armature position, in which it is held securely after the switching current is deactivated, i.e. in the non-energised state.
Electro-pneumatic hand brakes with a bistable solenoid valve device permit the pneumatic actuation of the hand brake, wherein it is not necessary to supply energy and thus no energy consumption is required when parked and/or when driving. Moreover, no current and thus no energy consumption is necessary during the drive, i.e. when the parking brake is disengaged.
Document DE 37 30 381 A1 discloses a bistable solenoid valve of this type, which makes permanent magnet holding force possible in both of its positions. An armature is provided here that can be displaced between its armature positions and that strikes at a first end core or a second end core in its armature positions, wherein an air gap is formed with the other end core in each instance. The effect of the air gap is that the permanent magnet field running through each end core is weaker than the permanent magnet field running between the other end core and the armature without an air gap. In its armature positions and/or valve positions, the armature closes off the respectively appropriate fluid passages with its sealing means.